Thyrotropin (TSH) glycosylation is regulated at early high-mannose precursor steps as well as late complex carbohydrate steps. Metabolic factors such as serum and glucose primarily regulate TSH-Alpha glycosylation while the endocrine factors TRH and thyroid hormone primarily regulate TSH-Beta. Subcellular fractionation studies indicate major differences in the translocation and carbohydrate processing of TSH, free TSH-Alpha and non-TSH cell glycoproteins.